1. Field of The Invention
The present invention relates generally to stripping or removing protective coatings from optical fibers, and more particularly to an apparatus for quickly and precisely stripping an outer buffer coating of an optical fiber prior to processing, without damaging the optical qualities of the optical fiber.
2. Background of the Related Art
A fiber optic cable typically comprises an optical fiber concentrically surrounded by a series of protective layers as generally shown in FIG. 1 and FIG. 6. More specifically, as shown in FIG. 1, the optical fiber 8 consists of a core region 10 that provides a path for optical signals traveling along the optical fiber. The core region 10 is surrounded by a cladding region 12 whose refractive index may be altered to achieve a desired propagation path of the optical signals traveling along the core region 10. The cladding region 12 is in turn surrounded by an outer protective coating 14 to protect the core region 10 and the cladding region 12 from damage, such as nicks, scratches or dents, which could degrade the long term quality and performance of the optical fiber.
As shown in FIG. 1 and FIG. 6, the optical fiber 8 is protected by a buffer layer 16. The buffer layer 16 is typically a firm polymer which provides increased protection to the fiber while also increasing the fiber bending stiffness. The buffer layer 16 is formed directly around the inner optical fiber 8 and there is usually a significant adhesive force between the buffer layer 16 and the protective coating 14 surrounding the optical fiber. The buffer layer may additionally comprise a soft polymer, such as acrylate, which coats and adheres to the glass fiber.
The buffer layer 16 is surrounded by strengthening fibers 17 (see FIG. 6), such as KEVLAR, to provide additional strength for pulling the fiber optic cable through conduit and for other applications. The outer layer 18 is typically a 3 mm polymer jacket similar to the jacketing surrounding standard electrical wire.
As is well known, electro-optical data transfer systems comprise a wide variety of interacting electrical, optical and electro-optical modules. In a typical data transfer system electrical signals are converted to light signals, the light signals are amplified, filtered, and/or multiplexed, and then converted back to electrical signals. The connections between the modules must be extremely precise, and must be carried out with the utmost care to avoid damaging the optical fibers.
During the manufacture of optical assemblies, the ends of the optical fibers may be joined together by a fusion process wherein the separate and confronting ends of the optical fibers are fused together. Alternatively, a connector may be placed on each of the confronting ends of the optical fiber and thereafter the connectors are coupled together using, for example, a bulkhead. Moreover, a connector may also be used for connecting an optical fiber and an electro-optical module.
For example, in the conventional in-line amplifier of FIG. 2, light entering the amplifier 21 is amplified using a laser pump 22. The laser pump 22 itself contains an optical fiber lead which is connected to the amplifier module 21. However, prior to making the connections, the buffer layer 16 must be stripped or removed from the lead of the laser pump 22. The buffer layer 16 must be removed because the laser lead must be wrapped into a fiber cassette, and, with the buffer layer attached, there is insufficient space to accommodate the laser lead in the cassette.
However, using conventional mechanical and thermal stripping methods to remove the buffer layer, it was found that more than 50% of the laser leads were rendered unusable due to damage to the underlying optical fiber during the buffer layer removal process. This not only reduces the throughput of the electro-optical assembly, it significantly adds to the cost of the assembly due to the waste of the optical resource or component, i.e., the laser pump. Moreover, nicks or damage to the outer coating during the buffer layer removal process may cause light dispersion in the optical fiber, thereby degrading its performance. Such nicks or damage can also lead to early failures or otherwise reduce the serviceable life of the optical fiber.
Accordingly, a need exits for an apparatus that can quickly and effectively remove the buffer coating from an optical fiber, without damaging or nicking the outer coating of an optical fiber.